Control system for hydraulic presses



G. A. WALIE ETAL. ZA'EEEfiSB CONTROL SYSTEM FOR HYDRAULIC PRESSES Jam. 2, 194?.

Filed Aug. 5, 1942 Q SHeetS-Sheet 1 INVENTOR5 I Gsonar. A. Warm;

don-um A. Muusw.

ATTORNEY5 a. A. WALDEE ETAL ZAES QSS CONTROL SYSTEM FOR HYDRAULIC PRESSES Filed Aug. 3, 1942 2 Sheets-Sheet 2 2: 33 q; crfi- Q 12.

v INVENTOR I8 qe Gzonc: A.WALDIE JQHAN A. MuLuaw Y ATTORNEYS Patented Jan. 28, 1947 I CONTROL SYSTEM FOR HYDRAULIC PRESSES George A. Waldie, Edison, and Johan A. Muller, Dayton, Ohio, assignors to The Hydraulic Development Corporation, Inc., Wilmington, Del., a corporation of Delaware Application August 3, 1942, Serial No. 453,376

This invention relates to control systems and,

in particular, to electric control systems for hydraulic machinery.

It is well known that when a hydraulic press 11 Claims.

able plunger and electric drivin means for driving said fluid source, in which safety means is provided which prevents the plunger from starting a working cycle if the plunger occupies a postands idle fora relatively long period of time, sition intermediate its end positions while the the press ram gradually slides or creeps downdriving means is being started.

wardly due to leakage around hydraulically oper- A further object of the invention consists' in able driving means operatively connected with the provision of a control system for hydraulic th pre s1ram When'then th press is to be put machinery, .which includes a fluid source of variinto operation, the ram has first to be returned able delivery for S p g p e fluid to a to its retracted or starting position. In case tne fluid operable plunger, and in which the speed :driving fluid is upp ied by a pump of the variable of the plunger is automatically slowed down when delivery type, it is customary, for the sake of simit approaches a predetermined p in of travel. plicity, to positively connect the said pump with and has-its speed automatically increased again an electric motor for driving the pump, so that following the said slow down.

when the electric motoris started, also the pump is started, while substantially simultaneously the pump is automatically moved into return stroke position, if it does not already occupy the said a return stroke position. v

' Since, under these circumstances, the'- electric motor has to start under full load when, aftera relatively long period of idleness of the press, the .ram has to be returned to its retracted or starting position, special starter means is required to protect the electric motor. Furthermore, the power required for this initial or conditioning operation is relatively high, n It is, therefore, an object of this invention to provide a-contro1' system which may be used in connection with hydraulic ing the above mentioned drawbacks.

It is another object of the invention to provide a control system for hydraulic machinery, such as presses, which includes a pressure fluid source of variable delivery and electric driving means therefor, and in which automatic means is provided adapted to allow the fluid source to supplyits full delivery to the hydraulic machin-- cry for actuating the same only after the driving means has been brought up to its full speed. Itisanother object to provide a control system eluding a fluid source of pplyingfipressure fluid to a ource, ;in "which; startingyof the driving a siautomatieally causes the fluid source to er. pressure fluid,- said plunger after the speed, thereby causing;-

.and-, ele ctric driving means for. driving said d ng means has bee throught up to a desired he plunger to move to It is a still further object of the invention to provide a control system as set forth above, which includes stop meansoperable at any desired point Dresses for remedyof travel of a fluid operable plunger for halting the latter virtually instantaneously.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

Figure l diagrammatically illustrates a press circuit in connection with which the control system according to the invention may be used.

Figure 2 shows a variation of somedetails illustrated in Figure 1.

Figure 3 is an electric ing to the invention.

General arrangement The electric circuit according to the invention is illustrated by way of example in connection With the control mechanism shown in' Figures 1 and 2, which control mechanism comprises two th'rustors connected-with a variable delivery pump in such a manner that actuation of one thruster shifts the pump into full stroke delivery position, whereas the other thrustor, when moved into a first position, causes a reduction in the delivery oi the pump and, when moved into a second position, causes the pump to move into substantially neutral or no delivery position When the control system according to the invention is used in connection with a hydraulic press supplied with pressure fluid from a variable delivery pump, and the press ram, after a period of idleness, is to he returned from a position incontrol system accordpredetermined point, which. it stops auto, termediateits endpositions to its initial or start- "m5, 59, I U ing position, a starter or conditioning switch'is still another object to provide a control actuated. vThe actuation of this switch autoystem inclliding, a fluid source of variabl delivmatically causes first the second mentioned eryifor supplying pressure fluid to'a fluid operthruster to positively move the pump into or hold Tauaocs 3 the same in its neutral position, and thereafter starts the driving motor for the pump. when the driving motor has been brought up to full speed, the pump is automatically shifted into full deliv ery retraction stroke position, thereby returning the press rain to its retracted or starting position. .When the ram has reached this position, it automatically comes to a stop, irrespective of whether or not the press has previously been conautomatic operation. i. e., autoditioned for full matically to start a working cycle whenever the press ram has been returned to its retracted or starting position.

Figure 1, it will engage and stop the arm 2| when the latter moves downwardly from the position shown in Figure 1.

The three arm lever '62 is shiftable about a pivot 29 and has its arm 30 pivotally connected to a control or thrustor rod 3|, which latter is pivotally connected to the element 32 pertaining to an electrically controlled thrustor T1. The

To start a working cycle'of the press ram, an

electric circuit is closed by actuation of aswitch,

whereupon the press ram automatically advances;

its retracted position, whereas it immediately starts a new cycle in case the press was conditioned for full automatic operation.

The electric control system according to the invention alsov includes means which may be operated at any desired'point of travel-of the ram for bringing the latter to a substantially instantaneous stop.

Structural arrangement Referring now to the drawings in detail, the

right hand-end of the lever arm 39 has connected thereto oneend of a spring 33, the other end of which is'connected to a stationary element 3 1.v

The third arm of the three arm lever i2 is pivotally connected to a link 33 which is fiv'otally connected to a flow control rod 31 pertaining to a variable delivery. pump, generally designated '3B,-' and provided; with .a servomotor 39. ump 38 is adaptedtof be driven-by a prime f meterone and the sameishaftl' and maybe arranged in the manner disclosedgin the Emst, Patent No.

The pump 38 is preferably of the type shown in the Ernst Patent No... $184,665, in which fluid from the pilot pump vis'adapted to shift the flow control rod 31 selectively intoyforward or return stroke position. Furt fii nd e. centering spr n not shown in the drawings, are-provided in 'a manner similar to that-disclosed in the said i Patent No. 2,184,665, which springs-tend to hold the pump in neutral or no delivery'position.

From the above it will beclear that when the: motor PM is started, also the pumps 38 and are started. The pump 38 has hydraulic connections 4| and 42 respectively leading tothe upper and lower portions of the press cylinder i. .The'-hy:-'

press system shown in Figure 1 comprises a press cylinder I having reciprocably mounted therein a press ram, generally designated 2, including a piston 3 and piston rods 4 and 5.

Connected to the piston rod 4 is aplaten 6 with a platen arm I, which latter is adapted to cooperate with a collar 8 adjustably mounted on a push rod 9. The push rod 9 is guided on the press frame in any conventional manner, not shown in the drawings.

Also adjustably connected to the push rod 9 a is a collar III for cooperation with an arm ll of a three arm lever, generally designated l2. The arm ll carries a pin l3 extending into a slot ll of a control or thrustor rod IS; The rod l5 has adjustably connected thereto an abutment l6 engaged by the upper end of a spring ll, the lower end of which engages a portion connected to a stationary member, which may, for instance, be th press frame. The rod iihas also adjustably connected thereto a collar l9 for abutment with the portion la. The lower end'of the control or thrustor rod I5 is pivotally connected to'an' element 20 adapted to be actuated by an electrically controlled thrustor T2.

The adjustable abutment l3 has connected theretoan arm-2| with an inclined end surface 22 which is adapted to cooperate with a similarly shaped rod 23. The rod 23 has adjustably mounted thereon an abutment 24 engaged by one end of a spring 25, while the other end of this spring engages a stationary element 26. The rod 23, also carries, adiustably mounted thereon, a collar 21 adapted to abut thestationary element 26. The rod 23 has connected thereto an armature 23, controlled by a solenoid S. The arrangement is such that when the rod 23 occupies its outermost right hand position with regard to draulic connection M communicateswitha conduit 43 leading to a tonnage control valve of any conventional type, for instance, of the type disclosed in the Ernst Patent-No. 2,224,957. This tonnage control valve 44 is adapted, in response to a predetermined pressure, to open the tonnage control switch TC.

The platen 6 is adapted; when in its retracted or starting position, to close a normally open limit switch LS2. The platen 6 carries a cam 45 .adapted, at a predetermined point of travel of; the ram, to close a normally open limit switch when the pump 38 is substantially in neutral or no delivery position, the arm 35 of the three arm lever 12 closesthe limit switch LS1.

The arrangement of Figure 2 differs from that of Figure]. merely in that the solenoid S and 50 and 5|. 'The valves 49, 59' and 5| arefin their turn controlled by the solenoids S', T: and

T'r, Since otherwise the structure of Figure 2 fully corresponds to that of Figure 1,similar elemerits in Figure 2, have been designated withthe same reference numerals they havein Figure 1, however, with the additional letter a. Referring now to Figure 3, showing the electric These cylinder-piston-assemblies.are sup- The control circuit according to the invention also comprises a limit switch LS1, which'is closedwhen the three arm lever 12 occupies a position. v corresponding substantially to the neutralor no delivery position of the pump 38. In other words,';

. main supply line 59 adapted to 2,41p,ots

control system according to the invention, the

switches controlled by one and the same contacand also comprises a main supply line 53.. The .line 52 is adapted, by closure of the starter or conditioning switch ST, to be connected with a line 54 leading to one end of the contactor A, the other end of which is connected to the main sup- 3 ply line 53.

Branching ofi from the line 54 is a line 55 adapted, by closure of the switch m, to be connected with a line 56, which latter is connected with the line 52 through the time blade TB when the latter is in closed position. The time blade TB is controlled by a timer motor TM having one formance of a single terminal connected to the main supply line 53,

while the other terminal is adapted to be connected with the line 52 by closure of the switch a2. Also connected with the line 52 is a line 51 adapted, by closure of the switch f1,.to be connected with one end of the solenoid S,-the other end of which is connected to the mainsupply line 53. The solenoid S is also adaptedto be connected with the line 52 by closure of the switch Branching off from the line 51 is a line 58 adapted, by closure of the switch ii, to be connected with one end of a contactor B, the other end of which is connected with the main supply,

line 53. The contactor B is also adapted ,to be connected with the line 52 through the line 59, the switch a4, temperature switch TH and the tonnage control switch TC, when the said switches are in their closed position.

Branching oif from the line 59 is a line 60.

adapted, by closure of the limit switch LS3, to be connected with the line 6| leading to the line 62, The'line 62 is adapted electrically to communicate through the normally closed switch 14 with one end of the contactor C, the other end of which communicates with the main supply line 53. The contactor C is also adapted, by closure of the switch is, to be, connected with the line 58. The line 62 is adapted to be electrically connected with the line- 63 by closure of the switch as. The line 63 is adapted electrically to communicate with the line 52 through the line 64 and the closed switches TH and TC.

Connected with the-line 63. is a hand-automatic operation switch 65 which when in closed position, conditions the press circuit for automatic operation, whereas the switch 65, when'in open position, conditions the press circuit for hand operation. 66 indicates a. dead contact which. may be engaged by the switch 65 when the latter is in open position.

Connected with the switch 65 is a line 61 adapted to be connected with a line 68 through the reversing switch 69 and the switch as when these switches are in closed position. It should be noted that the switch as is normally closed. The line 68 is adapted, by closure of the switch or, to be connected with the line 10 leading to the line 62.

The line 61 may also be connected with the line 10 through the limit switch LS2, the line 1 I and the forward push button switches 12 and 73 when the said three switches are in closed position.

terminal of the prime Connected with the main supply. line 53 is one end of a contactor D, the other end of which may be connected through closure of the switch at with one terminal of the limit switch LS1, the

other terminal ofwhich is connected to a line 14 which, by closure of the motor stop switch 15, is connected with the line 52. I

Branching off from the line 14 is a line 18 adapted, by closure of the switch d1, to be connected with the contactor D.

Connected with the main supply line 53 is a contactor E adapted to electrically communicate with the terminal 11 through the normally closed switch is. The terminal 11 is adapted to be connected with the line 18 by closure of the switch 19. When the switch 19 engages the terminal 11, the press circuit is conditioned for full automaticoperation, i. e., for the performance of an indefinite number of cycles, whereas when the switch 19 is open, the press circuit is conditioned for semi-automatic operation, 1. e., for the percycle, after which the press automatically stops. When the switch 19 is open, it may engage the dead contact 80.

The line 18 is adapted through the normally closed switch aa to communicate with the line 8| leading to the line 1|. Branching off from the line 18 is a line 82 adapted, by closure of the a switch c1, to communicate with the line 52.- Connected with the line 52 is a line 83 which, by closure of the switch d2 may communicate with one mover or motor 'PM, the other terminal of which is connected through the line 84 with the main supplyline 53.

Connected to the main supply line 53 is the electrically controlled thrustor Tl adapted, by closure ofthe switch 02 to communicate with the line 52. The thruster T2 has one terminal connected to the main supply line 53, and is adapted to be electrically connected, through closure of the switch b1, with the line 52. Connected to the line 52 are two terminals 85 and 86 adapted respectively to be connected to the terminals 81 and 88- by closure of the emergency stop buttons 89 and 90. The terminals8'l and 88 are connected through line 9| with one end of the contactor F, the other end of which is connected to the main supply line 53.

Connected to the line 9| is a line 92 adapted, by closure of the switch ft, to be connected with the terminals 93 and 94, which terminals are adapted, by closure of the restarter buttons or switches 95 and 96 respectively to be connected with the terminals 91 and 98, which in their turn are connected to the line 52.

Operation end, the operatorcloses the master switch 5|; and furthermore closes the starter or conditioning switch ST. As a result thereof, electric current flows from the main supply line 58 through switch ST line 54 supply line 53. In

and contactor A to the main this way, the contactor A is energized so that the switches a1, as, as, m, as and a'z-close, whereas the switches at and as open. Y

Closure or the switch a; establishes a holding circuit for the contactor A, which holding circuit comprises main supply line 58, line 52, time blade TB,'switch a1, lines 55 and 54, contactor A and main supply line 53.

Closure of the switch a: establishes the energizing circuit for the timer motor TM, which ciraz, timer motor TM and main supply line 53. In this way, the timer motor TM starts to operate.

Closure of the switch as closes -a circuitcomprising main supply line 58, line 52, switch as, solenoid S and main supply line 53. As a result thereof, the solenoid S is energized and: moves the rod 23 (Figure 1) toward the left so as to move the latter out of the path'of the arm 2|.

Closure of the switch at establishes a circuit comprising main supply line 50, line 52, switches TC, TH and at, line 59, contactor B and main supply line 53. As a result thereof, the contactor B isenergized and causes the switch in to close. Closure of the switch in establishes an energizing circuit for the thrustor-Tn, which circuit comprisesmain supply line 50, line 52, switch b1,

thrustor T2 and main supply line 53. As a re sult thereof, the thrustor T2 causes the rod l (Figure 1) to move all the way down as far as the coils of spring l| will permit. When this happens, the upper end of the slot It has, by means of the pin l3, moved the lever l2 into the position shown in .Figure 1, thereby positively holding the pump 38 in substantially neutral or no delivery position. As previously mentioned, in this position of the three arm lever l2, the limit switch 1 81 is closed.

Closure of the switch as causes energization of the contactor C through the main supply line 50, line 52, switches TC and TH, lines. and 63, switch as, line 62, normally closed switch it, contactor C and main supply line 53. Energizathm of the contactor C causes the switches ci and oz to close. Closure of the switch 01 has no defect at this'time, since the switch as is open. Closure of the switch C2 causes energization of the thrustor TrthlOllgh main supply line 50, line 52, switch c2, thrustor T1 and the main supply line 53; As a result thereof, the thrustor T1 tends, 5

by means of the rod 3l- (Figure l), to move the three arm lever [2 in clockwise direction. However, since the thrustor T2 is stronger than the Closure of the switch a-: at the time when this closure occurs, does not energize the contactor D,-sin ce; at this time, the limit switch LS1 is open.

However, when, due to the energization of the thrustor T2, the thrustor rod l5 has shifted the three arm lever I2 into the position shown in Figure l and has, thereby, closed the limit switch LS1, the energizing circuit for the contactor D is closed, This energizing circuit comprises main supply line 58, line 52, switches I5, LS1 and a1, contactor D and the main supply line'53. Energization of the contactor D causes closure of the switches (11 and d2. Closure of the switch (11 establishes a. holding circuit for the contactor D, which holding circuit comprises the main supply line 58, line 52, switch 15, line 16, switch d1,

contactor D and the main supply line 53.

.10 'cuit comprises main supply line 58, line 52, switch Closure of the switch d2 closes the energizing circuit for the motor PM, which circuit comprises 'main supply line 50, line 52; line 83, switch (12, motor PM and main supply line 53. As a result 5 thereof, the motor PM starts and, due'to its driving connection with the pump 38 and the pilot pump 40, also starts these pumps. However, since the pump 38 is positively held in substantially its neutral or no delivery position, as mentioned above, pilot fluid from the pilot pump is prevented from shifting the pump 38 on stroke. The fluid delivered by the pilot pump 48, for the period during which the motor PM is brought up to its desired speed, is by-passed. A predetermined time thereafter the timer motor TM has reached its full speed and, having been set accordingly, opens the time blade TB.

, Opening of the-time blade TB breaks the energizing circuit for the contactor -A, so that the the switches at and Ge close. Opening of the switch ai prevents reenergization of the contactor A when the time blade TB automatically returns to its closing position shortly after it moved into its open position. Opening oi. the switch as breaks the energizing circuit for. the timer motor TM, so that the latter stops. Opening of the switch aa'breaks the energizing'circuit for the solenoid S. Opening of the switch 114 breaks the energizing circuit for the contactor B, so that the switch in opens. Opening of, the switch b1 causes 'deenergization of the thrustor T2. Opening of the'switch a5 breaks the energizing circuit for the contactor C, so that the switches 01 and cc open. Opening of the switch (:1 prevents reenergization of the contactor 0 when the switch as closes. Opening of the switch as deenergizes the thrustor T1. ,Opening of the switch at has no particular efthe spring 33 is now free to shift. the three arm lever l2 in anti-clockwise direction, so that fluid from the pilot pump shifts the pump 38 into full delivery retraction stroke position. Thereafter the delivery of the pilot pump is 0 again by-passed to an exhaust. Since, at the time when this shifting of the pump 38 into full delivery retraction stroke position is efiected,

the motor PM and pump 38 are at full speed, movement of the pump 38 into. its retracted position is carried out smoothly without undue load on the motor PM.

D Pressure fluid delivered by the pump 38 now passes through conduit -42 into the lower portion of the press cylinder I, whilefluid is withdrawn from the upper portion of the cylinder I by m the pump 38 through conduit 4|. Consequently,

the ram 2 now moves upwardly. .When the ram, during this upward movement, approaches 7 the position shown in Figure l, theplaten arm a l engages the collar 8 and lifts the push rod 9 so that the collar l0 engages the left end of the lever arm ll, thereby moving the lever l2 in clockwise direction. When the ram 2 has reached the position shown in Figure l, the lever 7 'I2 is likewise in the position of Figure l, in which position it has caused the flow control rod 31 to bring about movement of the pump 38 to its neutral or no delivery position. As a result thereof, the press ram is halted in the position 7 shown in Figure 1.

switches a1, (12, as. a4, as and 0.1 open, whereas feet, since the switch a7 is by-passed through It may now be assumed that the-operator desires to cause the press automatically to carry out a plurality of pressing cycles. In other words, the press is to be conditioned for full automatic operation. To this end, the switch 65 is closed so as to interconnect the lines 61 and 63. This conditions the press for automatic matic operation, the closes the switch I9 so as to connect the lines 11. and I8 with each other.

To start the first pressing cycle, both forward push button switches I2 and I3 are closed. This the thrustor T2,

operation. To condition the press for full autooperator additiona1ly immediately causes energizationof the contactor.

' that this switch LS2 is the switch which is adapted to bring about repeat strokes of the press when the latter is conditioned for full automatic operation.

Energization of the contactor C closes the switches 01 and c2, of which the switch 01 establishes a holding circuit for the contactor C, as previously mentioned, while the closure of switch 02 causes energization of the thrustor T1. Energization of the thrustor T1 moves the element 32 downwardly against the thrust of the spring 33,

thereby shifting the pump- 38 into full delivery forward stroke position. Pressure fluid is now delivered by the pump 38 through conduit 4I into the upper portion of the press cylinder I, while fluid is withdrawn from the lower portion of the press cylinder I. ram 2 moves downwardly.

In addition to bringing about energization of the contactor C, the closure'of the forward push button switches I2 and 13 also sets up another actuating circuit, which circuit comprises mainsupply line 50, line-52, switches TC and TH, line 64, switches 65, I2 and I3, line 8|, switches as, 19 and f5, contactor E and main supply line 53. As a result thereof, the contactor E is energized and causes the switch e1 to close. switch e1 establishes a holding circuitfor the contactor E, which holding circuit comprises main supply .line 50, line 52, switch e1, line I8, switches I9 and f5, contactor E and main supply line 53, so that the contactor E'Temains energized when, after starting of the pressing cycle, the forward push button'switches l2 and I3 are. released and automatical returned to their open position. l

It will also be notedthat this circuit brings about the automatic initiation of the next cycle when the press platen 6, at the end of the present Closure of the Consequently, the press 10 B1, which latter closes the energizing circuit for as previously described.

Inasmuch as the thrustor T2 is stronger than the thrustor T1, as mentioned above, the armature 28 causes the thrustor rod I5 to shift the three arm lever I2 in anti-clockwise direction through the intervention of the pin I3. The

downward movement of the rod I5 and, thereby also the movement of the three arm lever I2 in anti-clockwise direction comes to a halt when the arm 2| engages the rod 23. When this occurs,

.the lever I2 has shifted the pump 38 into a restricted delivery position so that now only a reduced quantity of fluid is supplied by the pump 38 through the conduit 4I into the upper portion of the press cylinder I, and a corresponding reduced quantity of fluid is withdrawn from the lower portion of the cylinder I. Consequently, the downward movement of the press platen 6 is being 'slowed down. The period platen 6 is being slowed down depends on the shape of the cam and the restricted delivery position of the pump 38. When the cam 45 of the platen 6, during the downward movement, of

the latter, releases the switch LS3, this switch automatically returns to its open position, thereby breaking the energizing circuit for the contactor B. Consequently, the switch b1 opens and the thrustor T2 becomes deenergized. Since the thrustor T! is still energized, it again shifts the three arm lever I2 in clockwise direction so as .to move the pump 33 again into its full delivery forward stroke position. Therefore, the delivery of the pump 38 to the upper portion of the press cylinder I is again increased, thereby restoring the advancing speed of the press ram.

When, at-the end of the actual pressing operation, a predetermined pressure has been established in the conduit 4|, this pressure is con-- veyed through conduit 43 to the tonnage control valve '44 and brings about opening of the tonnage control switch TC.. This breaks the holding circycle, closes the limit switch LS2, so that current flows from the main supply line 50 through cuit for the contactor C and, thereby, causes deene-rgization thereof. Deenergization of the contactor C causes the switches ciuand cc to return tov their open position.

Opening of the switch ci'prevents reenergization of the contactor C when the tonnage control switch C automatically returns to its closing position shortly after it was opened by the tonnage control valve 44. Opening of the switch 02 breaks the energizing circuit for the thrustor T1, thereby allowing the spring 33 to move the three arm lever I2 in anti-clockwise direction so as to move the pump 38 into full stroke retraction position. The pump 38 then delivers pressure fluid through the conduit 42 to the lower portion of the press cylinder I, while fluid is withdrawn from the upper portion of the cylinder I through the conduit 4|. As a result, the ram 2 now moves upwardly. When the ram reaches the position shown in Figure 1, it has again closed the limit switch LS2 and, since the contactor E is still energized, the closure of the limit switch LS2 closes the energizing circuit for the contactor C, as previously described, so that the press auto-. matically starts a new cycle. 1

If the press had not been conditioned for full the press would stop since, at the end of its retraction stroke, the platen arm 'I engages the for which the If it should happen that, during theoperation of the press, the operating 'fluid, which in general is oil, reaches an undue temperature, the temperature switch TH automatically opens, thereby breaking the energizing circuits for the contactors B and C, so that the press is automatically returned to its initial or starting position. The operator, noticing this automatic reversal, may then either open the switch '19, if it isnot open at that time, to cause the press to stop at the end of its retraction stroke in the manner described above, or he may close the emergency stop buttons 89, 90 to virtually instantaneously stop the press.

Closure oi. the emergency stop buttons 89, 90 brings about energization ofthe emergency contactor F through the main supply line 50. line 52. switches 89 and 90. line 9!, contactor F and main supply line 53; Energization of the contactor F causes the switches f1. f2, f3 and fa to close and the switches f4 and is to open. Closure of the switch is establishes a holding circuit for the contactor F, which holding circuit comprises the mainsupply line 50, line 52, restarter button or switch 95. switch fa, line 92, contactor F and the main supply line 53.

Closure of the switches f1, f2 and f3 brings about energization of the solenoid S and contactors B and C. As a result thereof. also the thrustors T1 and T2 are energized. Therefore, the solenoid S withdraws the rod 23 from the path of the arm 2 l, and the thrustor T2 shifts the three arm lever l2 in anti-clockwise direction so as to cause the pump 38 to move into neutral position in the manner previously described.

Energization, of the thrustor T1 is ineffective at this time since, as mentioned above, the

thrustor T2,, is stronger than the' thrustor T1.

Consequently.- no fluid is supplied to or withdrawn from the cylinder I so that the press ram comes to a halt. If after such emergency stop, the press is to be restarted. the emergency contactor F is to be deenergized by opening of the restarter buttons or switches 95 and 96. It is to be noted that the pressing of the emergency stop buttons 89 or 90 is effective substantially simultaneously to bring the ram to a halt whether it is moving on its upward or downward stroke. Thereafter, the deenergization of the emergency contactor F by the opening of the switches 55 and 96 will be effective to cause the ram to return to'its fully retracted position. This is due to the fact that the contactor C will be de-energized upon de- 32 If it is desired to control thepress by hand rather than automatically, the switch 55 is opened, thereby preventing energization of the contactors B and C and, thereby, also of the thrustors Trand-Tr. In other words, the electric control circuit, as far as it controls the press during itscycle, is dead, and the pump may then be controlled manually in conventional manner for operation of the press.

It will be understood that we desire tocompr'ehend within our invention such modifications as come within the scope of the claims.

Having thus fully described our invention.

a what we claim as new and desire to secure by motor, a prime mover connected to drive said.

source, said motor having a movable element continuously urged in one direction and being adapted during the movement thereof in the other direction to move said source to neutral, means continuously urging said source toward position to deliver to said motor in a direction to move said element in said other direction, first control means operable to move said source to neutral, means responsive to the actuation of said first control means to start said prime mover, second control means operable to make said first control means ineffective while maintaining said prime mover in operation, and a control circuit 4 operable automatically to actuate said first con-v trol means and after a predetermined time delay to actuate said second control means.

2. In a control system, a fluid motor having a movable element continuously urged in its advancing direction, a fluid source for supplying said motor and having a flow control member, ,means operated by said element during movement in its retracting direction for moving said member to neutral, yielding means continuously urging said member to cause said sourceto deliver to said motor in a direction to move said element in its retracting direction, an electrically controlled prime mover drivingly connected with said source, first control means operable to poenergization of F and will not close again upon closing of the contacts 14 because the holding circuit including the blades cl is also open. The contactor E can be again energized to place the press in full automatic operation by closing the start buttons 12 and 13. It will be apparent that operate to clear the circuit of its full automatic conditioning, but provides for automatic recycling so long as the contactor E remains energized.

sition, said member in neutral, means operable automatically upon the actuation of said first control means to energize said prime mover, second control means operable to make said first control means ineffective, and an electrical control circuit energizable to actuate said first and second control means automatically and in sequence, and to maintain said prime mover energized following the actuation of said second control 'means.

3. In a control system, a vertically reciprocable plunger, a variable delivery pump connected to supply said plunger, said plunger being adapted in its uppermost position to move said pump to neutral, an electric motor positively connected to drive said pump, a first thrustor operable to urge said pump into position to deliver to the upper end of said plunger, a second thruster operable to position said pump in neutral against the thrust of said first thruster, control means selectively operable for actuating both of said thrustors to position said pump in neutral, means automatically operable when said pump is in neutral for energizing said motor, and means automatically operable a predetermined time after said motor is energized for making said thrustors inefiective.

4. In a control system, a vertically reciprocable plunger having advancing and retracting means,

'to deliver to said retracting means, means operated by the plunger in its fully retracted position for moving said pump to neutral, first electrically 14 cluding a plunger vertically reciprocable by a downward acting advancing area and an upward acting retracting area and also including a variable delivery 'pump which is continuously urged controlled means operable to move said pump into position to deliver'to said advancing means, second electrically controlled means operable to move said pump to neutral against the thrust of said first electrically operable means when said electric motor'is to be started, means for energizing both of said electrically controlled means for positively positioning said pump in neutral, means automatically operable in response to the positioning of said pump in' neutral for energizing said electric motor, and means comprising time delay means operable automatically after a predetermined period following the energization of said motor for de-energizing said first and second electrically controlled means.

5. In a control system, a vertically reciprocable plunger having a downward acting advancing area and an upward acting retracting area, a reversible variabledelivery pump connected to supply said areaameans operated by said plunger as it approaches its fully retracted position for moving said pump toward neutral, an electric motor directly coupled with said pump, yielding means continuously urging said pump toward position to deliver to said retracting area, a first thrustor operable to move said pump into position to deliver to said advancing area, a second thrustor operable to move said pump to neutral against the-thrust'of said first thrustor, and means operable when said motor is to be started and said plunger is below its fully retracted position for actuating both of said thrustors to position said pump in neutral thereby to prevent its delivery to said plunger, means automatically operable thereafter for energizing said motor,- means responsive to a predetermined time delay following the energization of said motor for rendering said thrustors ineffective, and means selectively operable thereafter for actuating or rendering inefiective said first thrustor for reciprocating said plunger.

6. In a control system. a vertically reciprocable plunger having a downward acting advancing area and an upward acting retracting area, a reversible variable delivery fluid source adapted to supply actuating fluid to said areas, yielding means continuously urging said source to deliver to said retracting area, means operated by said plunger as it approaches its fully retracted posi- I tion for moving said source toward neutral, an electric motor positively-drivingly connected with said source so that both are placed into operation simultaneously, a first electrical thrustor operable to place said pump in position to deliver to said advancing area, a second and larger electrical thrustor adapted to place said pump in neutral when said first thrustor isenergized, and electric control circuit meansv operable when said motor is to be started and said plunger is below its fully retracted position for positively preventing the energization of said motor prior to the placing of said pump in neutral, said control" circuit means being adapted automatically first to energize both of said thrustor-s, thereafter to energize said motor, and finally to de-energize ,said thrustors while continuing the energization of said motor,

7. In combinatidn with a hydraulic systcni in-.

by yielding means to deliver to said retracting area and which is positivelydrivingly connected with an electric motor, means operated by the plunger in its fully retracted position to move the said pump to neutral, electric control circuit means operable automatically to start said electric motor and said pump ,while simultaneously preventing fluid connection between said pump and said advancing and retracting areas, and a predetermined time thereafter to establish fluid connection to cause said' plunger to return to its retracted or starting position from a position intermediate its end positions, means operatively connected with said electric control circuit means for conditioning said hydraulic-system to cause saidplunger to initiate automatically a plurality ofgcy'cles thereof, and means associated with said eleetr'lc control circuit means for preventing said plunger from automatically starting an advancing stroke following the movement of said plunger from the said intermediate position to its retracted or starting position. I

8. In a control system including aplunger having associated therewith fluid operable advancing and retracting means for reciprocating the same and also including conditioning means for-conditioning said control system for full automatic operation so as to cause said plunger automatically to start another cycle following the completion of one cycle, a variable delivery pump for supplying pressure fluid selectively to said advancing or retracting means, yielding means continuously urging said pump to deliver to said retracting means, electric motor means positively drivingly connected with said pump for starting the same simultaneously with the starting of said motor means, first control means for moving said pump to neutral while said pump and said motor means are being started and brought up to a predetermined speed, second control means actuatedautomatically after a predetermined delay during which said pump and said motor means have reached predetermined speed for making said moving meansinoperative while continuing said pump and motor in operation, whereby-said yielding means may move said pump to deliver to the retracting means if the plunger has moved away from its retracted position, third control means responsive to the return of said plunger to said retracted position for shifting said pump to substantially neutral or no delivery position and maintaining said pump in this position irrespective of the conditioning of said control system for full automatic operation, and electric circuit means for automatically and-successively actuating said first and second control means.

9, In a control system for-a plunger having advancing and retracting areas and a pump connected therewith continuously urged to deliver to said retracting area, said pump having a means for interrupting delivery of saidpumpto said plunger while saidprime mover and pump are brought up to speed, second control means for making said first control means inefiective while maintaining said prime mover in operation, third control means responsive to the movement of said plunger to fullyv retracted; position to interrupt delivery of said pump to said plunger,

"1s 7 ii emer ency stopmeans selectively operable subbe retracted and remain in retracted position regardless of the conditioning of the system.-

I'O. In a control system for a plungerIhaving advancing and retracting areas and a pump connectedltherewith continuously urged to deliver to said retracting area, said pump having a prime mover positively connected therewith; means to condition said system ior fullautomatic cycling ofsaid plunger, first control means for interruptingdelivery of said pump to said plunger while said prime mover and pump are brought up to speed, second control means for making said first prime mover in operation, third control means responsive to the movement'of said plunger to said pump to said plunger, emergency electrical means selectively energizeaole substantially in- ,stantaneously to halt the movement of said plunger during the cycling thereof, means responsive to thedeenergization of said emergency means to return said plunger toits fully retracted position; and means responsive to the actuation offsaid emergency means when said system is conditioned for full automatic operation for al- --te ri ng the said conditioning so that the said control means inefiective while maintaining said I ,20 fully retracted position. to interrupt delivery of 11. In a control system for a plunger having advancing and retracting areas and a source of v i pressure fluid connected therewith which is continuously urged to deliver to said retracting means, saidsource having a. prime-mover positively connected therewith, means of conditioning said control system for full automatic cycling of said plunger, first control means for moving said source to neutral delivery position while said prime mover and.v source are brought up to speed, second control means for making said first control means i'nefiective while maintaining said prime mover inoperation, third control means responsive to [the movement of said plunger to fully retracted position to move said source to neutral delivery position, an electrical circuit operable to energize said first and second control means automatically and in sequence, emergency stop meansselectively operable substantiallyiina stantaneously to halt the movement ofsaid plunger during the cycling thereof means operable after the operation of said stop means for returning said plunger directly to its retracted position, andineans for maintaining said plunger in its fully. retracted position irrespective of the I v conditioning of said circuit when moved theretoj I following thestarting of. said prime mover or V the actuationof said stop means, H Q GEORGE A. WALDI'E; JOHAN A.

plunger comes to a halt in its retracted position. r 

